For some apps I want to use external speakers, like Spotify for music.
Some apps I want to use only in phone speakers, like browser.
Some apps for earbuds, like messengers.
Would be nice if phones let us setup priority for bt devices and bind specific apps for specific bt devices or make order for bt devices (if connected to buds and a car first send sound to buds).
I don't know if it has all the functionality you're looking for but have you tried "separate so sound" in settings? Is in settings > sounds and vibrations " separate so sounds.
I think it only allows you to play some sounds through a Bluetooth speaker while others stay from the phone's speaker.
